In the application of paints by electrodeposition to automobile wheels, bodies and other types of articles, the customary process involves immersing the article in an electrodeposition paint bath to which a current is applied in order to cause the solids in said bath including resins and binders to be electrodeposited on the article. In the usual type of paint electrodeposition process the article becomes the anode and the electrodeposited solids consist essentially of negatively charged particles. In the electrodeposition of paint one type of process which is used employs an electrodeposition aqueous coating bath containing particulate pigment and polycarboxylic acid resin binder. This type of process is disclosed in U.S. Pat. No. 3,699,030 patented Oct. 17, 1972, and in various other patents referred to therein, all of which are incorporated herein by reference.
After the paint has been electrodeposited on the article the article is removed from the bath and the paint drippings and paint contained in water used to wash the article present a disposal problem. The solids are usually quite tacky and tend to cling to the floors and walls and any other surfaces with which they come into contact. This causes formation of deposits on such surfaces that are difficult to remove. Usually, the drippings and wash water containing electrodeposition paint solids are removed in any suitable manner and in order to avoid contamination of the environment it is customary to separate the solids from the water and recirculate the water but the separation of the solids is difficult by the usual method of filtration. Moreover, because of the tackiness of the solids, the removal of the waste water, including the drippings and the wash water, does not necessarily remove all of the solids from the surrounding surfaces and this makes it necessary to shut down the operation from time to time in order to clean such surfaces.
It is therefore desirable to control pollution and contamination in electrodeposition paint operations so as to prevent, as much as possible, the deposition of paint solids on surrounding surfaces which are exposed to drippings and wash water from the painted articles and to condition the sludge which is removed with the water so that it can be readily filtered and the water which forms the filtrate can be returned for further use.